YES SEE SHEET 2
(BLOCK 1A)

Pressure in the Bleed Air Duct Is Not Constant during the Main Engine Start
Figure 126 (Sheet 1)

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A13034
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FROM SHEET 1 (BLOCK 1)
YES
YES SEE SHEET 3 (BLOCK 2)

NO

21WARNINGDO NOT OPERATE THE APU WITH THE LOWER SHROUD REMOVED IF PERSONS ARE IN OR DIRECTLY BELOW THE APU COMPARTMENT. YOU MUST BE A MINIMUM OF 3 FEET AWAY FROM THE OUTER EDGE OF THE APU COMPARTMENT OPENING TO OPERATE THE APU WITH THE LOWER SHROUD REMOVED. AN APU TURBINE WHEEL SEPARA-TION DURING OPERATION CAN CAUSE INJURY TO PERSONS.
EXAMINE THE CIRCUIT FROM THE 3-WAY SOLENOID VALVE,CONNECTOR D1574, PIN A, TO THE APU SHROUD, CONNECTOR D452, PIN S (WDM 49-31-01).
IS THE CIRCUIT OK?
NO

YES
NO

21A EXAMINE THE CIRCUIT FROM
THE 3-WAY SOLENOID VALVE,
CONNECTOR D1574, PIN B, TO
GROUND (WDM 49-31-01).

IS THE CIRCUIT OK?

YES NO
21B MEASURE THE RESISTANCE AT
THE 3-WAY SOLENOID VALVE,
CONNECTOR D1574, FROM PIN A TO
PIN B (WDM 49-31-01).
IS THE RESISTANCE 35-110 OHMS?

YES
NO

21C EXAMINE CONNECTORS D1450
51D REPAIR OR REPLACE THE
AND D474 FOR THE BLEED AIR BLEED AIR VALVE, V56,
VALVE FOR CORROSION AND CONNECTORS D1450 AND D474, AS
DAMAGE. NECESSARY.

ARE THE CONNECTORS OK? IF NECESSARY, REPLACE THE

Pressure in the Bleed Air Duct Is Not Constant during the Main Engine Start
Figure 126 (Sheet 2)

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F11606
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FROM SHEET 2 (BLOCK 1A)

TO THE 3-WAY SOLENOID VALVE.BLEED AIR VALVE, V56,
EXAMINE CONNECTORS D1450 CONNECTORS D1450 AND D474 AS AND D474 FOR THE BLEED AIR NECESSARY. VALVE FOR CORROSION AND IF NECESSARY, REPLACE THE DAMAGE. BLEED AIR VALVE, V56
ARE THE CONNECTORS OK? (AMM 49-52-11/401).

APU (AMM 49-11-00/201). AND AGAIN? DOES THE BLEED AIR VALVE OPERATE OPEN AND CLOSED AGAIN  (FIG. 124). CLOSED AGAIN AND AGAIN AIR VALVE OPERATES OPEN AND
NO 
(BLOCK 7) SEE SHEET 4 

Pressure in the Bleed Air Duct Is Not Constant during the Main Engine Start
Figure 126 (Sheet 3)

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FROM SHEET 3 (BLOCK 6)

NO

YES
7
DO A CHECK OF THE FILTER
ELEMENT FOR THE LOW-PRESSURE
FUEL (AMM 49-31-22/401).

IS THE FILTER CLOGGED?

NO

YES
8
DO A CHECK OF THE FILTER
FOR THE HIGH-PRESSURE FUEL
(AMM 49-31-81/301).

IS THE FILTER CLOGGED?

NO
NO

9 DO THE TEST FOR THE
59 ADJUST THE OPENING PRES-OPENING PRESSURE OF THE
SURE FOR THE ACCELERATIONACCELERATION LIMITER VALVE
LIMITER VALVE (AMM 49-11-00/ (AMM 49-11-00/501).
501). DID THE ACCELERATION LIMITER VALVE OPEN AT 60 |5 PSIG (414 |34 kPa)?

YES
NO

10 EXAMINE THE CIRCUIT FROM
THE TACHOMETER GENERATOR, CON-NECTOR D1262, PIN A, TO THE
ELECTRONIC SPEED SWITCH, S634,
CONNECTOR D1245, PIN H
(WDM 49-31-01; 49-41-01).

IS THE CIRCUIT OK?
YES YES
　
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